An unsaturated polyester resin, an epoxy resin, or a polyurethane resin has been conventionally used for coating of floor surfaces, wall surfaces, pavement surfaces of roads, and the like. However, the unsaturated polyester resin is not so good in weather resistance, causes large contraction at the time of curing, and is insufficient in workability at a low temperature, though it is excellent in solvent resistance. The epoxy resin is not good in weather resistance, takes long time in curing, and is not so good in curability at a low temperature, though it is excellent in alkali resistance and adherence to a substrate. The polyurethane resin is not so good in chemical resistance and weather resistance, though it is excellent in elasticity and flexibility.
Consequently, a vinyl ester resin or an acrylic resin which is excellent in curability at a low temperature, weather resistance, and chemical resistance has been used in recent years. However, the vinyl ester resin and the acrylic resin have a problem of odor at the time of operation because they have peculiar odor originated from a low molecular mass monomer such as styrene or methyl methacrylate.
In recent years, people have been getting more concerned about environmental problems, and use of a material containing a volatile and highly odor-producing component such as an organic solvent or a low molecular mass monomer tends to be limited. Consequently, a syrup composition with low odor obtained by using a monomer having a high molecular mass or a monomer having a high boiling point has been proposed.    (1) An acrylic syrup composition containing a (meth)acrylate monomer which contains at least a heterocyclic ring-containing (meth)acrylate monomer, at least one of a polymer and a radical polymerizable oligomer, and a crosslinking agent (Patent Document 1).    (2) An acrylic syrup composition containing a (meth)acrylate monomer having a boiling point of 75° C. or higher at 6.67 kPa, a polymer or a radical polymerizable oligomer, and a wax in a state of dispersion (Patent Document 2).    (3) A resin composition containing a resin having a (meth)acryloyl group at the end of a molecule, an air-drying endowing type polymer obtained by using at least one of a drying oil and its aliphatic acid compound, and an ethylenically unsaturated monomer having a (meth)acryloyl group with a molecular mass of 160 or more (Patent Document 3).    (4) A resin composition containing a resin having a polymerizable unsaturated group, an acrylic monomer having a phenyl group and a molecular mass of 180 to 500, and a hydroxyalkyl (meth)acrylate having an alkyl group with 1 to 4 carbon atoms (Patent Document 4).    (5) A resin composition containing a polyether acrylic urethane resin having a (meth)acryloyl group at the end of a molecule, an unsaturated polyester resin using a drying oil as an alcoholysis compound, an air-drying endowing type polymer selected from an unsaturated polyester resin or an alkyd resin which is obtained by using at least one of a drying oil and its aliphatic acid compound, and an ethylenically unsaturated monomer having a (meth)acryloyl group with a molecular mass of 160 or more (Patent Document 5).    (6) A curable resin composition containing an epoxy (meth)acrylate comprising a reaction product of a (meth)acrylic acid and an epoxy compound obtained by reacting 1.5 to 3.5 moles of an aliphatic diglycidylether type epoxy compound having an epoxy equivalent of 300 or less with 1.0 mole of at least one of bisphenol A and bisphenol F, and a polymerizable (meth)acrylic monomer having a molecular mass of 160 or more and a viscosity of 100 mPa·s or less at 25° C. (Patent Document 6).
However, every syrup composition of (1) to (6) has a problem that curability at a portion contacting to air (surface curability) is lowered because a monomer with low reactivity is used. Consequently, it is necessary to use a polyvalent metal soap as a curing accelerator to improve the surface curability. However, there is a problem that finished appearance is affected by the polyvalent metal soap because the polyvalent metal soap forms a complex in the course of polymerization of a monomer to cause coloring in the coating film to be obtained.    Patent Document 1: Japanese Patent Application Laid-Open No. 2000-154297    Patent Document 2: Japanese Patent Application Laid-Open No. 2002-234921    Patent Document 3: Japanese Patent Application Laid-Open No. 8-283357    Patent Document 4: Japanese Patent Application Laid-Open No. 2004-203949    Patent Document 5: Japanese Patent Application Laid-Open No. 2004-323860    Patent Document 6: Japanese Patent Application Laid-Open No. 2001-240632